From 8c6712250d142cf758ab440750b482b786ed1718 Mon Sep 17 00:00:00 2001
From: honeybadgerdontcare <sedano@google.com>
Date: Wed, 16 Oct 2019 14:02:27 -0700
Subject: [PATCH] Do not strip <script type=text/plain> when children of
 template (amp-mustache).

PiperOrigin-RevId: 275108293
---
 transformer/transformers/stripjs.go      | 10 ++++++++--
 transformer/transformers/stripjs_test.go | 12 +++++++++++-
 2 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/transformer/transformers/stripjs.go b/transformer/transformers/stripjs.go
index 7d383e5d0..ae8f20f11 100644
--- a/transformer/transformers/stripjs.go
+++ b/transformer/transformers/stripjs.go
@@ -32,9 +32,10 @@ var eventRE = func() *regexp.Regexp {
 
 // StripJS removes non-AMP javascript from the DOM.
 // - For <script> elements, remove where any of the following is true:
-//     - has a src attribute whose value is not prefixed by https://cdn.ampproject.org/ (case-insensitive match).
+//     - It has a src attribute whose value is not prefixed by https://cdn.ampproject.org/ (case-insensitive match).
 //     - It has no src attribute and no type attribute (case-insensitive match).
 //     - It has a type attribute whose value is neither application/json nor application/ld+json (case-insensitive match on both name and value).
+//       - Unless it is a child of template (amp-mustache) and has type=text/plain.
 //
 // - For all other elements, remove any event attribute that matches "on[A-Za-z].*".
 func StripJS(e *Context) error {
@@ -63,10 +64,15 @@ func StripJS(e *Context) error {
 				case "application/json", "application/ld+json":
 					// ok to keep
 				case "text/javascript":
-					// ok to keep only for AMP Cache scripts.
+					// ok to keep only for AMP Cache scripts
 					if !isCacheSrc {
 						htmlnode.RemoveNode(&n)
 					}
+				case "text/plain":
+					// ok to keep only for children of template (amp-mustache)
+					if !htmlnode.IsDescendantOf(n, atom.Template) {
+						htmlnode.RemoveNode(&n)
+					}
 				default:
 					htmlnode.RemoveNode(&n)
 				}
diff --git a/transformer/transformers/stripjs_test.go b/transformer/transformers/stripjs_test.go
index fe3004f8a..e10b4d413 100644
--- a/transformer/transformers/stripjs_test.go
+++ b/transformer/transformers/stripjs_test.go
@@ -57,10 +57,20 @@ func TestStripJS(t *testing.T) {
 			Expected: "<head></head><body></body>",
 		},
 		{
-			Desc:     "keeps script corect type",
+			Desc:     "keeps script correct type",
 			Input:    "<script type=application/json>foo</script>",
 			Expected: "<head><script type=application/json>foo</script></head><body></body>",
 		},
+		{
+			Desc:     "keep type=text/plain when child of template (amp-mustache)",
+			Input:    "<body><template type=amp-mustache><script type=text/plain></script></template></body>",
+			Expected: "<body><template type=amp-mustache><script type=text/plain></script></template></body>",
+		},
+		{
+			Desc:     "strips type=text/plain when not child of template (amp-mustache)",
+			Input:    "<body><script type=text/plain></script></body>",
+			Expected: "<body></body>",
+		},
 		{
 			Desc:     "strip tag attr ona",
 			Input:    "<body><select ona=\"myFunction()\"></body>",
